THE BUD-ROT OF PALMS IN INDIA. 235 



the heart of the crown and in diseased trees probably emerge from 

 the pupal state within the disintegrating mass. Here they would 

 be likely to come into contact with not only mycelium but spores 

 which would adhere to their bodies. One or two observations 

 bear on this point. The disease is noticeably severe around the 

 huts of the "Madigas," alow class of Pariahs who eat the carcases 

 of animals, and also near the huts of fishermen and other low castes. 

 This may be due to the presence in such localities of the of¥al of 

 animals, fish, etc., which would attract birds and insects. In the 

 village of Ramachendrapur this fact was particularly visible. The 

 rate of spread is, however, too slow to make it probable that birds 

 play any considerable part, and, on the whole, though insects are 

 probably responsible for some of the spread, their share is likely to 

 be much less than that of the palm climbers. 



While, therefore, the way in which infection is spread in 

 individual cases has not been conclusively found, the methods con- 

 sidered above, particularly those connected with the stripping of the 

 leaves by human agency, are probably sufficient to account for the 

 conditions observed. 



IV.— Spkcies affected and course (^f the disease. 



As already mentioned, four species of palm are common 

 in the Delta, the palmyra (Borassus flabellifer), the coconut (Cocos 

 nucifera), the areca (Areca Catechu) and the date (Phoenix sylves- 

 tris). Of these the first three are subject to the disease, while the 

 date, so far as has been observed up to the present, is immune. 



By far the greatest mortality has occurred amongst palmyras. 

 Probably over half a million have been attacked within tlie affected 

 area. Coconuts have suffered much less. In an enumeration of 

 the diseased palms in the Mummidivaram Firka of Amalapur in 

 1907, less than 1 per cent, were found to be coconuts (46,527 pal- 

 myras, 455 coconuts). This disparity in numbers is not entirelv 

 due to the much greater quantity of palmyras than of coconuts 

 actually growing in the area in question. In several places there 

 are large gardens of coconuts surrounded by severely diseased 



